\documentclass[]{standalone} 

\usepackage{pgfplots} 

\pgfplotsset{compat=1.13}

\pgfplotsset{
/pgfplots/layers/mylayer/.define layer set=
{axis background,axis grid,main,axis ticks,axis lines,axis tick labels,%
axis descriptions,axis foreground}
{/pgfplots/layers/standard}
}


\begin{document}

\begin{tikzpicture}
        \pgfplotsset{set layers=mylayer}%
        \begin{axis}[
                axis x line=bottom,
                axis y line=left,   
				axis line style={line width=1pt},
			 %	enlargelimits=false,
                ymajorgrids = true,
            ]%

            \addplot[red,line width=3pt] coordinates {(0.0,0.0)(20,1)(40,0)(100,0)};
        \end{axis}%
\end{tikzpicture}%

\end{document}
